It is known to provide agricultural vehicles such as combines with a container for temporarily storing grain that the combine has harvested and threshed. Operatively connected with these containers are unloading tubes through which the grain from the container passes during grain unloading operations. An auger is typically positioned within the unloading tube for directing grain from the container into and through the unloading tube. As grain is unloaded from the combine's grain container through the unloading tube in this manner the grain is expelled into a truck or grain cart traveling next to the combine.
Many conventional unloading tubes include a generally upright lower portion operatively connected with and extending upwardly from a lower portion of the combine grain container. An upper portion of the unloader tube extends generally horizontally and is operatively coupled with the upper end portion of the upright portion. Augers are typically positioned within the lower and upper portions of the unloader tube. A gearbox is provided at the junction of the upper and lower portions of the unloader tube for operatively connecting the auger sections in the two portions of the unloader tube.
Conventional unloader tubes are adapted to pivot between two positions about the central axis of the lower portion of the tube. In a first position the upper portion of the unloader tube is positioned generally longitudinally with respect to the vehicle and is located in close proximity along the side of the vehicle, as shown in FIG. 1. The unloader tube can be swung outwardly from this position about the central axis of the lower portion to a position whereat the upper portion of the tube extends generally laterally outwardly from the side of the combine. The outer end of the unloader tube is positioned relatively high in the air such that a grain truck or cart can be positioned under the end of the tube to receive the grain being propelled from the tube.
The unloader tubes tend to be relatively heavy structures, since they house the augers and bear a large amount of weight when they carry heavy amounts of grain during operation. The unloader tubes must therefore be braced to withstand these forces during operation. The lower portion of the unloader tubes are held firmly in position by a sturdy support ring structure that supports the lower portion of the tube and allows the unloader to tube to pivot. Conventional combines also typically include an upper support structure above the tube's lower portion. The upper support mechanism helps keep the lower portion of the tube generally upright and helps keep the lower portion from toppling over due to the weight of the tube, augers and grain within the tube.
One type of conventional upper support mechanism includes a pin member closely aligned with the axis of the lower portion of the unloader tube. The pin is received within a tubular structure fixed with the side of the combine. The lower portion of the tube is manufactured and assembled to relatively exact tolerances so that the pin member is relatively precisely located in alignment with the axis of the lower portion of the tube. Also, the tubular structure and the brackets which hold it in place are manufactured and assembled to relatively exact tolerances so that the axis of the tubular structure is held in position in relatively precise alignment with the axis of the pin member. The processes of manufacturing and assembling all these parts to exact tolerances are relatively costly and time consuming, and raises the complexity and cost of the combine.
Another type of conventional upper support mechanism includes a metal pin member generally aligned with the axis of the lower portion of the unloader tube. The lower portion of the tube is not manufactured or assembled to exact tolerances, so the pin may be slightly misaligned from the axis of the lower portion of the unloader tube. This misalignment can cause the pin to shift in various directions as the unloader tube swings between its two positions. The pin is slidably received within a metal bearing member held within a metal housing. The bearing is free to swivel within the metal housing, and the pin is free to slide up and down within the bearing member. Therefore misalignment of the pin and housing member from the exact axis of the lower portion of the unloader tube is compensated for by the freedom of motion of the pin with respect to the housing member. This type of upper support mechanism is relatively inexpensive to manufacture and assemble since it is not manufactured to exact tolerances. However, the metal bearing member swivels in contact with the metal housing member, and the pin slides in contact with the bearing, and therefore the support requires lubrication so as to avoid excessive wear. This type of upper support mechanism therefore requires regular maintenance so that lubrication can be applied to the bearing surfaces within the structure.
It would therefore be desirable to provide an upper support mechanism which helps retain a combine unloader tube in its proper upright position during operation such as when filled with grain, and which does not require lubrication at regular intervals. It would also be desirable for such a mechanism to not require manufacturing or assembly processes having exact tolerences. It would be desirable for such a mechanism to allow for motion that might occur due to slight misalignments of the upper support structure from the actual axis of the lower portion of the unloader tube. It would be desirable to reduce the cost and complexity of the assembly process and the mechanism itself.